1. Field of the Invention
The present invention relates to a mechanism for preventing a cartridge from being inserted in the incorrect direction and in particular, the mechanism for use with a magnetic tape apparatus.
2. The Prior Art
FIG. 1 shows the structure of a conventional tray locking mechanism. Referring to FIG. 1, lock lever 11 is rotatably mounted on a cartridge tray with pin 2-8. In the state that a cartridge has not been inserted, since lock lever securing portion 11-2 disposed on lock lever 11 is pressed to lock pin 4-7 with a predetermined means (not shown), lock lever 11 prevents the cartridge tray from being moved (this state is referred to as loading lock). In this state, since lock lever 11 protrudes, unless cartridge 1 is inserted in the correct direction, front end portion 11-1 blocks the cartridge, thereby preventing cartridge 1 from being loaded. On the other hand, when cartridge 1 is inserted in the correct direction, front end portion 11-1 is raised along notch 1-1, thereby causing the loading lock to be deactivated. Thus, in the conventional mechanism, lock lever 11 functions as both the loading lock operation and the mis-insertion preventing mechanism.
In the conventional mechanism, the timing at which the loading lock is deactivated is early. In other words, before the cartridge 1 is inserted into the position at which the cartridge 1 is securely locked, the loading lock is deactivated. Thus, a loading malfunction takes place. As a result, reel face gear 1-4 is improperly engaged with drive motor face gear 10.